The EMD SD9

The EMD SD9, also referred to as a "Cadillac" for the smooth, soft ride, was the builder's second model in its six-axle series and
looked virtually identical to the SD7. Slightly more powerful than its
predecessor and using an updated version of General Motors' proven prime mover
of the time, the model 567, the SD9 was the most successful
first-generation six-axle locomotive EMD produced, selling more than 500
examples (which included sales to foreign railroads). Apparently, the
bump up in horsepower convinced more lines to try the locomotive.
Still, the Electro-Motive Division found sales difficult with numerous
future six-axle models. Until the SD40 was released in 1966 only the
SD24 and SD35 sold more than 100 units for the company. As with many
early model EMDs the SD9 soldiers on today, finding use in regular
service on shortlines and industrial settings. There are also several
units officially preserved including Colorado & Southern #839 and
Southern Pacific #5428, #5363, #5468, and #5472.

The EMD SD9 began production in early 1954, soon after the SD7 line was closed. The model used GM's latest prime mover
of the time, the 16-cylinder model 567C which provided the SD9 a 1,750
horsepower rating, 250 more horsepower than the earlier SD7. Also,
using GM's model D47 traction motors
the C-C truck setup provided for a continuous tractive effort of 75,000
pounds (its starting tractive effort was nearly 91,000 pounds), which
also closely mirrored the SD7. While the locomotive had the option of
an added steam boiler for use in
passenger service only a few railroads would include the feature with
their SD9s including the Duluth, Missabe & Iron Range Railroad, Burlington, and Southern Pacific.

The Southern Pacific was one of the first railroads to take notice of
the extra tractive effort EMD's Special Duty line provided, especially
in mountainous operations, and purchased the most SD7s by a single
company. They likewise purchased the most SD9s, buying 150 of the 471
total sold to domestic railroads (another 44 were purchased by foreign
lines). While the 515 SD9s ultimately sold paled in comparison to the
more than 4,000 four-axle GP9s outshopped, more railroads took notice of
the latest six-axle design with more than a dozen Class Is purchasing
the model. Many of the companies that purchased the SD9 had also bought or tested
at least one SD7.

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